DECLARATIVE HYBRID ROUTING PROTOCOLS IN AD HOC NETWORKS

This paper presents adaptive hybrid protocols based on the declarative network and mainly discusses the principle and realization of the Bayesian-estimation based adaptive hybrid protocol in the declarative network, which is well adapted to the Mobile Ad hoc NETwork (MANET). The adaptive hybrid protocol is designed for ad hoc networks which have characteristics like self-organizing, no trusted party, flexibility, etc. The nodes that run the hybrid protocol can automatically select one routing protocol that is suitable for different network environment. The Bayesian-estimation based adaptive strategy, that improves the adaptability and stability of the protocol, succeeds in the Rapidnet, a declarative network engine. The result in the Rapidnet proves that the hybrid protocol and the adaptive strategy are feasible. The experiment on the ns-3 simulator, an emerging discrete-event network simulator, validates that this protocol performs well and reduces communication overheads.

A FULLY-HYBRID MAC PROTOCOL IN LANS

In announced hybrid protocols,there are two mechanisms usually employed.One operates in aCSMA family manner and the other follows a token passing family way.However,only one ofthem works efficiently when traffic is light or heavy.This results in an inefficient redundance and aburden to the protocol implementation.In this paper,we present a new hybrid concept and its idealmodel in which risky transmissions alternate with safe transmissions in response to the dynamicchange in traffic.Being similar to virtual time CSMA in the abstract,a single control mechanism isproposed to approach this ideal model.The mechanism is rather compact,and its implementationcan be designed to be simple,efficient,reliable,robust,and fully distributed without any centralizedelement at any instant.Simulation results show that the proposed mechanism performs well overthe entire range of the traffic load from light to heavy.

A Hybrid Formal Description Method Based on FSM,CSP and ADT for Communication Protocol

Since communication protocol deals with complex issues related to distribution such as communication, concurrency and synchronization, their development needs to be traced by using sophisticated formal description methods. This paper presents a new hybrid formal method for communication protocol specification. In this method, finite state machine (FSM), communication sequential process (CSP) and abstract data type (ADT) are mixed and the best features of these approaches are offered. In this paper, the main formal description techniques (FDT) for protocol engineering are brieny introduced and a hybrid formal description method based on the FSM, CSP and ADT for communication protocol is described. Finally, this paper presents the formal specification of an example protocol for LAN by using the proposed hybrid formal method. The results of studies show that the hybrid formal description method for communication protocol is an available and effective approach.

Hierarchical hybrid control network design based on LON and master-slave RS-422/485 protocol

Aiming at the weaknesses of LON bus, combining the coexistence of fieldbus and DCS (Distribu ted Control Systems) in control networks, the authors introduce a hierarchical hybrid control network design based on LON and master slave RS 422/485 protocol. This design adopts LON as the trunk, master slave RS 422/485 control networks are connected to LON as special subnets by dedicated gateways. It is an implementation method for isomerous control network integration. Data management is ranked according to real time requirements for different network data. The core components, such as control network nodes, router and gateway, are detailed in the paper. The design utilizes both communication advantage of LonWorks technology and the more powerful control ability of universal MCUs or PLCs, thus it greatly increases system response speed and performance cost ratio.

SER analysis and power allocation for hybrid cooperative transmission system

The symbol-error-rate（SER） and power allocation for hybrid cooperative（HC） transmission system are investigated.Closed-form SER expression is derived by using the moment generating function（MGF）-based approach.However,the resultant SER contains an MGF of the harmonic mean of two independent random variables（RVs）,which is not tractable in SER analysis.We present a simple MGF expression of the harmonic mean of two independent RVs which avoids the hypergeometric functions used commonly in previous studies.Using the simple MGF,closed-form SER for HC system with M-ary phase shift keying（M-PSK） signals is provided.Further,an approximation as well as an upper bound of the SER is presented.It is shown that the SER approximation is asymptotically tight.Based on the tight SER approximation,the power allocation of the HC system is investigated.It is shown that the optimal power allocation does not depend on the fading parameters of the source-destination（SD） channel and it only depends on the source-relay（SR） and relay-destination（RD） channels.Moreover,the performance gain of the power allocation depends on the ratio of the channel quality between RD and SR.With the increase of this ratio,more performance gain can be acquired.

Performance analysis of QoS routing protocol for WiMedia networks

Though the WiMedia supports higher data rates than other WPAN technologies,a WiMedia device cannot reach other devices that are separated from it by more than 10 m,which is the typical limited transmission range of the WiMedia protocol.In this work,we propose a multi-hop QoS routing protocol to enable WiMedia devices to transmit real-time data to devices that are located out of the transmission range.The proposed routing protocol is a hybrid algorithm,which mixes the table-driven and on-demand routing algorithms,searching one or more routes according to the number of hops to a destination device.WiMedia MAC is potentially capable of learning the existence of neighbor devices by using a beacon frame.By utilizing the neighbors' information,all devices can create routing entries for devices within 2-hops periodically.For devices beyond the 2-hop range,the newly designed on-demand routing algorithm is applied to multi-hop routing.If a routing entry for a destination device is not listed in the routing table,the source device sends a request packet to 2-hop range devices which could be found in the routing table.Since every device maintains routing entries for 2-hop range devices in the routing table,the request packet is replied in advance before its arrival at the destination device.Also,to decide the optimal route for a destination device,the number of medium access slots(MASs),received signal strength indicator(RSSI)and hop count are utilized to establish a QoS-enabled routing table.We perform ns-2 simulation to investigate the performance of the proposed routing protocol with AODV and DSDV.The simulation results show that the proposed protocol has better throughput and lower overhead than other protocols.

Research on a Secure Communication Protocol Based on National Secret SM2 Algorithm

Most of the public key algorithms used in the exchange of information for power data transmission protocols are RSA. The core of the key part of this kind of algorithm system has not been announced. For the domestic sensitive information data field, there are threats such as preset backdoors and security vulnerabilities. In response to the above problems, the article introduces a secure communication protocol based on the optimized Secret SM2 algorithm, which uses socket programming to achieve two-way encrypted communication between clients and services, and is able to complete the security protection of data encryption transmission, authentication, data tampering, etc., and proves through experiments that the security protocol is more secure than traditional methods, can effectively identify each other, carry out stable and controllable data encryption transmission, and has good applicability.

Cooperative Layer-2 Based Routing Approach for Hybrid Wireless Mesh Networks

In a Wireless Mesh Network(WMN),the convenience of a routing strategy strongly depends on the mobility of the intermediate nodes that compose the paths.Taking this behaviour into account,this paper presents a routing scheme that works differently accordingly to the node mobility.In this sense,a proactive routing scheme is restricted to the backbone to promote the use of stable routes.Conversely,the reactive protocol is used for searching routes to or from a mobile destination.Both approaches are simultaneously implemented in the mesh nodes so that the routing protocols share routing information that optimises the network performance.Aimed at guaranteeing the IP compatibility,the combination of the two protocols in the core routers is carried out in the Medium Access Control(MAC)layer.In contrast to the operation in the IP layer where two routing protocols cannot work concurrently,the transfer of the routing tasks to the MAC layer enables the use of multiple independent forwarding tables.Simulation results show the advantage of the proposal in terms of packet losses and data delay.

Practical Routing Protocol Models to Improve Network Performance and Adequacy

The telecommunications network has become an essential facility of our daily life, which is the reason why a good number of the recent researches are directed to it. In this paper, the performance of routing protocols for selected network and the optimum way of utilizing the network resources is proposed, through improving the routing method protocols to obtain the most accurate communication models, which give the best network performance, taking into consideration that the protocol time interval to recalculate the future routing step is agreed to be our performance criteria, which is then used to determine the total amount of incoming traffic normalized at the best network performance with respect to the network capacity as well. Moreover, adaptive routing evaluation methods have been mathematically investigated in this work for telecommunication networks (TN), more precisely, developing the infrared radiation (IR) routing methods for hybrid TN applications, in terms of implementation conditions at a certain guaranteed quality of service, where we give a particular interest in analyzing routing methods based on the fact that the distribution information is contained in the routing variables, rather than in the state variables. The protocol that deals with the unbalanced traffic distribution over TN nodes has been investigated in this paper as well, and simulation results show good progress in the proposed protocol over the traditional protocols.

ElasticDAG:弹性图式区块链

图式区块链采用有向无环图(directed acyclic graph,DAG)的并行拓扑结构,相较于基于串行拓扑结构的传统链式区块链,能够显著提升系统性能,已受到业界广泛关注.然而,现有图式区块链的共识协议与存储模型高度耦合,缺乏灵活性,难以适应多元化应用需求.同时,大部分图式区块链在共识协议层面上缺乏灵活性,局限于概率性共识协议,难以兼顾确认延迟和安全性,尤其对于延迟敏感型应用很不友好.为此,提出弹性图式区块链系统ElasticDAG,其核心思想是将存储模型和共识协议进行解耦,让两者并行、独立地运行,从而灵活适配多元化应用.针对提升系统吞吐量和活性的需求,为存储模型设计自适应区块确认策略和基于划分的确认区块排序算法;针对降低交易确认延迟的需求,设计低延迟DAG区块链混合共识协议.实验结果表明,ElasticDAG原型系统在广域网下的吞吐量高达11 Mb/s,并具有10秒级确认性能.与OHIE相比,Elastic DAG在实现同等吞吐量的情况下,可将确认延迟降低17倍;与Haootia相比,Elastic DAG在实现同等共识延迟的情况下,可将安全性从91.04%提升到99.999914%.

网络切片可编程数据平面模型

可重构匹配表(reconfigurable match table, RMT)是一种可编程的数据包处理流水线架构。为了实现可编程数据平面对更多不同网络协议的支持,在该架构的基础上扩展逆解析器,使用扩展后的逆解析器以及两个RMT流水线组成一个协议无关的网络切片可编程数据平面模型。由于RMT架构中采用精简指令集,扩展后的逆解析器采用复杂指令集,因此称扩展后的架构为混合指令RMT(hybrid-instruction RMT, HiRMT)。HiRMT能够支持基于IPv6转发平面的段路由、SID(segment ID)的多语义、微分段技术、多协议标签交换技术,以及虚拟扩展局域网技术。该架构具有广阔的应用场景。在Corundum原型平台上进行了逆解析器模块的性能测试,结果表明扩展后的逆解析器能够使用较少的资源在数据包大小达到512 B时以100 Gbit/s的吞吐量进行处理。

AES RSA-SM2 Algorithm against Man-in-the-Middle Attack in IEC 60870-5-104 Protocol

The IEC60870-5-104 protocol lacks an integrated authentication mechanism during plaintext transmission, and is vulnerable to security threats, monitoring, tampering, or cutting off communication connections. In order to verify the security problems of 104 protocol, the 104 master-slave communication implemented DoS attacks, ARP spoofing and Ettercap packet filtering and other man-in-the-middle attacks. DoS attacks may damage the network functions of the 104 communication host, resulting in communication interruption. ARP spoofing damaged the data privacy of the 104 protocol, and Ettercap packet filtering cut off the communication connection between the master and the slave. In order to resist the man-in-the-middle attack, the AES and RSA hybrid encryption signature algorithm and the national secret SM2 elliptic curve algorithm are proposed. AES and RSA hybrid encryption increases the security strength of communication data and realizes identity authentication. The digital signature implemented by the SM2 algorithm can realize identity verification, ensure that the data has not been tampered with, and can ensure the integrity of the data. Both of them improve the communication security of the 104 protocol.

适用于水声传感器网络的混合路由协议

针对水声传感器网络中静态节点与移动节点不同路由设计需求,分析确定性路由和机会路由的特点,提出一种适用于水声传感器网络的混合路由协议(HRP-USN),将水声传感器网络区分为静态节点和移动节点开展设计。静态节点路由协议融合静态路由和动态路由优点,路由建立过程手动配置路由表,路由维护和重建过程采用联合MAC层反馈及聚焦转发控制的方式,兼顾自组织性和协议复杂性;移动节点采用机会路由,将数据以单跳方式发送到静态节点,自适应确定最优中继节点后按照已有路由传输到网关节点,利用水声信道广播特性,提升网络弱通信条件下数据包投递率。通过仿真分析,在不同节点移动速度和误码率条件下,HRP-USN数据包投递率明显优于其他传统路由协议,更加适合水声传感器网络。

OWC/RF混合通信系统研究进展

无线光/射频混合通信系统克服了单一通信系统的局限性,在最大发挥无线光通信优势的同时弥补了射频通信的不足,显著提高了链路的可用性和可靠性,为未来高速大容量的信息传输提供了独特的解决方案。对近年来无线光/射频混合通信系统的研究进展进行了综述,首先介绍了不同混合通信系统模型的工作原理与应用,然后讨论了混合通信系统所面临的挑战和解决方法,最后展望了无线光/射频混合通信系统的未来发展趋势,旨在为无线光/射频混合通信系统的进一步研究和发展奠定基础。

无线传感网混合类MAC协议研究综述

在无线传感网(WSN)体系结构中,介质访问控制(MAC)协议负责调配网络中节点的信道接入,具有保障网络高效通信的重要作用。混合类MAC协议综合了竞争类MAC协议以及调度类MAC协议的特点,在融合两种机制的优点的同时克服其缺点,为无线信道资源的分配提供了更加灵活和全面的策略。首先概述了无线传感网MAC协议设计要点及分类,然后重点分析了无线传感网中经典的混合类MAC协议及国内外前沿的研究进展,并进一步归纳对比了各协议运行机制、性能及不足,得出混合类MAC协议的应用相关性及差异性的结论,最后总结了无线传感网混合类MAC协议研究现状并指出了未来的研究重点,以期为相关领域的研究人员提供参考。

基于能量约束的Ad Hoc网络混合路由协议

当前Ad Hoc网络混合路由协议对于节点的能耗问题没有很好的解决方案,从而限制了该协议的应用。针对这一问题,提出了利用节点的剩余能量来决定TC信息传播距离的AODV与OLSR混合路由协议ECAOHR。通过这种方式,可以使节点在能量较低时,在保持网络连通性的同时更少地参与网络维护。理论分析和仿真研究表明,该方法能有效提高网络的生存时间和吞吐量。

基于无线多跳自组网的混合路由研究

随着大规模无线多跳自组网在军队通信、应急通信等领域的广泛应用,域路由协议(ZRP)作为一种混合路由协议,其灵活的路由发现和维护策略,使其在大规模网络中的应用受到了更多的关注。ZRP的域内路由协议以及域间路由协议的选取,对协议整体性能影响巨大。面向具有一定拓扑变化的大规模无线多跳自组网,基于传统ZRP框架,优化设计得到改进的域路由协议。改进协议中,域内路由协议采用具有更高路由有效性以及较小资源消耗的主动路由策略,域间路由协议则通过增加过期路由缓存机制降低网络控制开销。通过建模分析验证了改进协议的域内路由具有更高的有效性;通过软件模拟平台NS2仿真,验证了改进协议具有更优的性能。

Aμ-MAC:一种自适应的无线传感器网络MAC协议

结合基于竞争和调度机制的混合型方案是高效的无线传感器网络MAC协议的重要解决思路.μ-MAC是一种典型的混合型MAC协议,本文在深入研究μ-MAC的基础上,提出一种自适应的混合型协议Aμ-MAC.它针对动态流量的数据采集型应用,解决了μ-MAC中动态拓扑适应性及时钟同步问题,并提供了良好的流量自适应性.仿真结果表明,Aμ-MAC增强了协议的扩展性和适应性,具有更好的网络生存能力,而保留了与μ-MAC相近的节能效率和时延性能.

移动自组织网络中基于优化分簇的混合路由协议

针对移动自组织网络中分簇路由协议的特点,对不同尺寸簇的稳定性、维护开销等特性进行了分析,设计了保证网络性能最优的优化分簇策略,并在此基础上首次提出了基于优化分簇的混合分层路由协议(HOCR)。仿真实验结果表明,该协议明显提高了路径寻径效率和网络的健壮性,减少了网络维护开销,并且实现简单,特别适用于移动性较强、网络负荷较重的大规模移动自组网。

网络学习资源组织流程的优化方法研究与设计

针对网络学习资源组织流程的复杂性,进行组织流程优化设计,提高学习资源调度的效率,提出一种基于模糊PID控制的网络学习资源组织流程优化控制方法。首先构建网络学习资源组织流程控制的约束参量和控制目标函数,然后采用CDMA协同调度的混合协议进行网络学习资源的组织流程均衡配置,采用模糊PID神经网络控制模型进行组织流程控制目标函数的最优解特征分析,实现流程优化。最后进行仿真测试,结果表明,采用该网络学习资源组织流程能节省学习资源调度的任务开销,降低延时,提高学习资源分配效率。